1. Field of the Invention
The invention relates to video display systems, and more particularly to a memory allocation control system for selectively accessing rows of video information stored in a video display system memory unit in any order without requiring a reconstruction of the video information as originally stored in the memory unit.
2. Description of the Prior Art
Video display systems have generally stored rows of video information in display memories in a predetermined order. Each row of video information has been of a fixed length, and has been read from the memory unit sequentially in the order stored. In order to insert or delete rows of video information, a reconstruction of the video information within the memory has been required.
Typical of such prior art systems are those disclosed in U.S. Pat. No. 3,500,335 entitled "Random Access--Data Editing Communication Network"; and U.S. Pat. No. 4,068,225 entitled "Apparatus for Displaying how Information on a Cathode Ray Tube Display and Rolling Over Previously Displayed Lines", both assigned to the same assignee as the instant application.
U.S. Pat. No. 3,500,335 describes the digitally added data stored in a main memory which is organized in a manner such that it is suitably available for generation of a cyclic presentation on a television raster display.
U.S. Pat. No. 4,068,225 describes the continual adjustment of the addressing used to access locations within the internal memory by maintaining a count of the number of rows of information that have already been entered and adding the count to the row portion of each address used in accessing locations within memory.